1. Field of the Invention
The present invention generally relates to estimation systems for interpolating moving pictures between frames and, more particularly, to a system for generating a video image occurring at an arbitrary time t between video images provided at times n and n+1 and at an arbitrary time t after time n+1 for a time series of video images provided at discrete times 1, 2, . . . n, n+1, . . .
2. Description of the Related Art
In currently available television systems for mass media broadcasts, video images are output every one-thirtieth of a second to accurately express a moving picture. If, for example, only ten video images are output per second, a moving picture becomes hard to watch.
In the field of so-called animation, a number of slightly different video images are formed and output at the rate of 30 images per second, thereby obtaining a smooth moving picture. This causes the problem that a vast number of processes are required to form these images manually. However, if some intermediate images are omitted and these omitted images are then interpolated to form a moving picture, the number of processes can be considerably reduced.
Further, in the medical field, a user of an ultrasonic diagnostic machine may want to obtain continuous ultrasonic video images of, for example, a cardiac blood stream flow. However, in the present technology, there is the problem that only 30 continuous video images can be obtained per second.
Under such circumstances, an interframe interpolation system for effectively obtaining a video image at an arbitrary time t between times n and n+1 and at an arbitrary time t after time n+1 on the basis of video images given at discrete times n and n+1 is needed.
FIGS. 1A and 1B are schematic diagrams used to explain a conventional moving video image estimation system. FIG. 1A shows examples of time series video images at time n and time n+1, and FIG. 1B shows problems encountered with existing interframe interpolation systems.
When a video image at an arbitrary time t between time n and time n+1 is produced for time series video images given at discrete times 1, 2, . . . n, n+1, . . . {see FIG. 1A}. According to the prior-art real moving picture interpolation system, concentrations at every pixel of the video image at time n and the video image at time n+1 are interpolated linearly.
More specifically, when the video image at time n is expressed as I(x,y;n) and the video image at time n+1 is expressed as I(x,y;n+1), a video image J(x,y;t) to be produced at an intermediate time t between times n and n+1 is calculated from the following equation. EQU J(x,y;t)=(n+1-t)I(x,y;n)+(t-n)I(x,y;n+1)
In accordance with this conventional system, when the position and shape of an object in a video image are considerably changed between the frames, there is then the disadvantage that the video image of the object in the original frame will be doubly reproduced in the interpolated video image.